marten



T. H. NIARTEN.

DAVKT. v APPLICATION FlLED-AUG.21. 1918 1,80%,9'F. Patented May 27, 1919.

2 SHEETS-SHEET l.

15' Vania? THOMAS HENRY MABTEN, OF TORONTO, ONTARIO, CANADA.

DAVIT.

Specification of Letters Patent.

Patented May 27, 1919.

Application filed August 21, 1918. Serial No. 250,854.

To all whom it may concern Be it known that I, THoMAs HENRY Man- TEN, a subject of the King of Great Britain, and resident of the city of Toronto, county of York, Province of Ontario, Dominion of Canada have invented certain new and useful Improvements in Davits, as described in the following specification and illustrated in the accompanying drawings, that form part of the same.

The principal objects of this invention are to obviate the difficulties met with in the operation of ships davits under the extraordinary stresses to which such devices are subjected and to effectively prevent the distortion and consequent injury to the means for operating the davit boom, and further to render the davit safe to handle and insuring against binding of the parts in its operation.

The principal feature of the lnvention consists in the novel arrangement of a pivotal extension from the boom whereby the boom and the traveling support therefor are rigidly supported and stabilized against the varying stresses caused by the constantly changing relation of the load during the operation of the boom.

In the drawings, Figure 1 is a side elevational view of a davit constructed in accordance with this invention showing in full lines the arrangement of the boom extension with the upper end of the boom in an upright position and illustrating in dotted lines the position of the extension when the boom is swung outboard.

Fig. 2 is a vertical sectional end elevational view taken on the line a-Z of Fig. 1.

Fig. 3 is a side elevational view showing the boom extension in a different arrangement in relation to the boom, the parts being shown in full lines when the boom is in the upright position and in dotted lines with the boom extended outboard.

The principle involved in the present invention is applicable to many different forms of davits and is particularly adapted to the type of davit in which the boom is pivotally supported upon a traveling carriage operated by means of a screw spindle.

Referring to the accompanying drawings, the frame 1 is shown in the form of a rigid casting having a trackway 2 at the upper side. Upon this trackway is mounted a suitable cross head or trolley 3 which is adapted to slide or roll upon the trackway and is operated by means of a screw spindle at which is suitably journaled in the frame.

The boom 5 is pivotally mounted upon a transverse pin 6 secured to or extending through the cross head 3 and is preferably formed with a bifurcated lower end straddling the frame and cross head.

In the form of davit illustrated in Figs. 1 and 2, the lower end 7 of the boom extending below the pivot pin is offset in a forward direction being arranged at an obtuse angle in relation to the upper part of the boom. The lower extremity of the boom is connected to the lower part of the frame by a pivotal link 8 which extends from the boom end in a downward and inboard direction.

In the form shown in Fig. 3, the lower end 9 of the boom extends downwardly below the pivot pin practically in a straight line with the upper end of the boom and the lower extremity of said boom is connected to the frame by a pivotal link 10 which extends in an outboard direction from the end of the boom to its pivotal connection with the frame.

It is found in practice that davits constructed on the general lines described are subject to peculiarities of distortion in the boom through the constantly changing relation between the load and the point of support, the result of which is that the cross head is caused tobind upon the trackway and upon the operating spindle and such binding effect is extremely detrimental in that it distorts the spindle and causes permanent injury, as well as making the operation of the spindle extremely difiicult, if not im ossible.

11 order to overcome this condition I provide an extension from the boom which is adapted to oppose the torque of the boom when said boom is swung outboard and to absorb or form a counter force against the stresses which cause the binding of the cross head and spindle. This boom extension is here shown in the form of a bifurcated lever 11, the upper ends 12 of which are journaled upon the pivot pin 6. The lower end of the lever 11 is connected by means of link members 13 to the pivot pin 14 in the base. The form of connection between the ends of the links 13 and the lever 11 is here shown as a threaded bar 15 which extends through the lower end of the lever and is rigidly secured in the links.

Upon the threaded bar are placed the jam nuts 16 which are adapted to engage the lower end of the lever and to hold it in a definite plane of operation. This adjustment is very desirable as it facilitates the adjustment of the davit to the load, according to the variation in conditions, that is to say, any inaccuracies and variation in machine work in the fitting of. the boom, cross head and the pivot pin, maybe offset by the adjustment of the nuts 16 upon the cross bar 15 to efiect an opposing strain in the lever 11 to offset thetendency there may be in the boom to cause a tilting of the cross head and consequent jamming of the spindle.

It will of course be understood that the construction of the boom extension member may be varied considerably as also may the general construction of the davit without departing fromthe spirit of the invention so long as the boom is provided with a pivotal extension which is adaptedto stabilize the same against the varying stresses set up in the boom.

What I'claim as my invention is 1. In a davit, the combination with the frame, the boom and a traveling member supporting said boom, of a pivotal extension from said boom adapted to efiect a counteracting force against the distortion of the boom and the consequent binding of the operating parts. 7

2. In a davit, thecombination With the frame, the boom and a traveling ;member supporting said boom, of a lever member pivotally connected with the boom intermediate of its length and extending toward the base of the frame, and means-for maintaining said lever member in a stabilizing relationship to said boom to offset the distorting effect of the stressesof the load upon the boom.

3. In a davit, the combination with the frame, the boom and a traveling member supporting said boom, of a lever pivotally connected to said traveling member and extending in a downward direction therefrom, and a link connection between the lower end of said lever and the base of the frame.

4. In a davit, the combination with the frame having a trackway, a cross head adapted to travel on said trackway, a spindle operating said cross head and a boom pivotally mounted on said cross'head, of a lever member pivotally connected with the boom at the point of its connection with the cross head, said lever extending downwardly, and a link connection secured to the lower end of said lever and connected to the frame.

5. In a davit, the combination with the rigid frame having a trackw'ay, a cross head mounted on said trackway, a screw spindle operating said cross head, and a boom pivotally mounted on said cross head, of a bifurcated lever pivotally connected to the pivotal mounting of said boom and cross head, a link pivotally secured to the base, and means adjustably connecting said lever with said link.

6. In a davit, the combination -w ith a rigid frame having a trackway at the top, a cross head mounted on said trackway and a boom pivotally mounted on said cross head, of an extensionfrom the boom pivotally connected therewith and extending downwardly, and a link pivotally secured to the lower end of said extensionand pivotally connected to the frame andadapted to maintain the extension in a position'in' relation to the boom to offset the distortion of the boom through the effect of the load and [consequent distortion of. the crosshead.

THOMAS HENRYHMARTEN.

Copies of this patent may be obtained for five cents each, by addressing the jCoinmissioner of Patents,

Washington I). G. 5 

